1. Field of the Invention
The present invention relates to a method for producing a spinning nozzle plate, and in particular to a method for producing a spinning nozzle plate for the spinning of fibers which has funnel-shaped preliminary channels in flow communication with nozzle capillaries.
2. Background of the Art
A method of this type is disclosed and illustrated in German patent application No. P 3,517,730.6, which corresponds to U.S. patent application Ser. No. 06/863,989, filed May 16th, 1986, by Erwin Becker, and the present inventors Wolfgang Ehrfeld and Peter Hagmann.
When fibers of organic or inorganic material are produced in large-scale industrial systems, the starting material is pressed, in a flowable state, through spinning nozzle plates which are equipped with a plurality of spinning nozzle channels. In most cases, the spinning nozzle channels are composed of preliminary channels into which the material to be spun is fed and nozzle capillaries through which the material is discharged in the form of fibers, the nozzle capillaries being in flow communication with the substantially wider preliminary channels. The preliminary channels frequently have the shape of funnels which become narrower toward the nozzle capillaries with which they structurally communicate.
When preliminary channels and nozzle capillaries are produced separately, such as in the separate lithographic-electrolytic deposition steps according to U.S. patent application Ser. No. 06/863,989, an undesirable offset frequently occurs at the point of transition from the narrow end of the funnel-shaped preliminary channel to the nozzle capillary. These offsets are typically caused by photolithographic mask misalignments and/or distortions and produce undesirable perturbations in the flow of the material to be spun. The resulting spun fiber thickness and/or thickness continuity may vary unacceptably from product specifications, and a sharp offset edge can cause a non-uniform disruption in the continuity of the fiber as well.